The present invention relates to a semi-floating method and apparatus for testing and determining an axis of a sperical ball which axis includes its geometric center and its center of gravity.
The phenomenon of the weight center not being located exactly at the geometric center of a spherical ball is widely known. Various studies of this unbalanced condition have been made. In the case of a golf ball, this phenomenon is described in detail by Olson et al in U.S. Pat. No. 4,111,038. Their findings showed this unbalanced condition to cause a golf ball to possibly veer undesirably when being putted. Further recited in their invention is a method and apparatus for testing and locating an axis in an unbalanced golf ball containing both its geometric center as well as its center of gravity and a method for indelibly marking the uppermost point of this axis. Their findings allowed for a certain control over this undesirable veering when a tested and marked golf ball was being putted.
Their method for locating this axis involved floating the golf ball in a mixture of water and magnesuim sulfate. The magnesium sulfate increased the density of the mixture sufficiently to cause the golf ball to float.
Present invention does not utilize densifying agents to cause a ball to float but rather uses liquid vibration means for forcing a thin layer of liquid between the ball and its supporting surfaces thus causing the ball to be suspended from its supporting surfaces by this layer of liquid and, hence, the ball appears to float even though it may be completely submerged in the chosen liquid.
In the case of golf balls, persons skilled in the game of golf recognize the importance of this "out of balance" condition of golf balls and would be inclined to use this information were it readily available at reasonable cost.
In one embodiment of the invention, a cup is carefully manufactured such that its inner spherical diameter is slightly larger than the outer spherical diameter of the ball to be tested. Further, some of the ball supporting surfaces of the cup are removed such that a carefully controlled ratio exists between these remaining ball supporting surfaces and the surface area of the ball to be tested.
When a cup as described above containing a common golf ball to be tested is immersed in ordinary water, the ball does not float. If the water is then made to vibrate at a certain frequency rate and at a certain power level, the golf ball will appear to float in that it is forced from its supporting surfaces by a relatively thin layer of the vibrating water. Once forced from its supporting surfaces, the golf ball is caused to rotate by gravity until its heavy portion is at the lowermost position and, hence, the desired axis containing the center of gravity and geometric center will become vertical and thereby determined.
Common golf balls may be tested in this manner using ordinary tap water without the use of or need for densifying agents. Further, common golf balls may be tested at relatively high rates of speed and hence, low cost in this manner also.
Hence, it can be seen that any number of combinations of properly made spherical cups, spherical balls and liquids may be chosen and the balls to be tested made to appear to float in the chosen liquid by this liquid vibration means without the need for or use of densifying agents or the like.
Some spherical balls with differing specific gravities may require the use of liquids of higher specific gravities than water such as FREON 11 or FREON 113. Additionally, spherical ball and liquid combinations wherein the spherical ball has specific gravity ranges of approximately 1.1 to 7.9 and the liquid has specific gravity ranges of approximately 0.8 to 14.0 may be used.